TW201635855A - Microwave heating device - Google Patents

Abstract

A waveguide-structure antenna has a ceiling surface, sidewall surfaces, and front opening defining a waveguide structure section, and emits microwaves from the front opening to an object to be heated. The waveguide structure section has a coupling part which is joined with the ceiling surface and couples microwaves into an internal space of the waveguide structure section. The waveguide structure section emits circularly polarized waves into a heating chamber from at least one microwave emission opening that is formed in the ceiling surface. The at least one microwave emission opening includes at least a pair of microwave emission openings that are symmetrical with respect to a pipe axis of the waveguide structure section. The waveguide structure section has a flat area between the pair of microwave emission openings. According to this embodiment, it is possible to perform uniform heating and local heating of an object to be heated set in the heating chamber.

Description

Microwave heating device Field of invention

The present disclosure relates to a microwave heating apparatus such as a microwave oven that heats an object to be heated such as a food by microwave.

Background of the invention

In a microwave oven of a typical microwave heating apparatus, microwaves generated by a magnetron of a representative microwave generating unit are supplied to a metal heating chamber, and are placed in a heating chamber by microwave heating. Heated material.

In recent years, a microwave oven in which the entire flat bottom surface in the heating chamber is used as a mounting table has been put into practical use. In such a microwave oven, in order to cover the entire surface of the mounting table, the object to be heated is uniformly heated, and a rotating antenna is provided below the mounting table (see, for example, Japanese Patent Publication No. Sho 63-53678 (hereinafter, referred to as Patent Document 1) )). The rotary antenna disclosed in Patent Document 1 has a waveguide structure that is magnetically coupled to a waveguide that transmits microwaves from a magnetron.

FIG. 17 is a front cross-sectional view showing the configuration of the microwave oven 100 disclosed in Patent Document 1. As shown in FIG. 17, in the microwave oven 100, microwaves generated by the magnetron 101 are transmitted in the waveguide 102 to reach the coupling shaft 109.

The rotating antenna 103 has a sector shape in a plane view from above, and is coupled to the waveguide 102 by a coupling shaft 109, and is driven to rotate by the motor 105. The coupling shaft 109 can transmit the microwaves transmitted into the waveguide 102 to the rotating antenna 103 of the waveguide structure and function as a center of rotation of the rotating antenna 103.

The rotating antenna 103 has a radiation port 107 for radiating microwaves and a low impedance portion 106. The microwave radiated from the radiation port 107 is supplied into the heating chamber 104, and the object to be heated (not shown) placed on the mounting table 108 of the heating chamber 104 is heated by microwaves.

The rotating antenna 103 is rotated below the mounting table 108 in order to achieve uniformization of the heating distribution in the heating chamber 104.

In addition to uniformly heating the function of the entire heating chamber (uniform heating), for example, when the frozen food and the food at room temperature are placed in the heating chamber, in order to simultaneously heat the food, the load is carried out. The function of locally and concentratedly radiating microwaves (local heating) in the area where the frozen food is placed is necessary.

In order to achieve local heating, a microwave oven that controls the stop position of the rotating antenna according to the temperature distribution in the heating chamber detected by the infrared sensor has been proposed (for example, Japanese Patent No. 2894250 (hereinafter, referred to as patent document) 2)).

FIG. 18 is a front cross-sectional view showing the configuration of the microwave oven 200 disclosed in Patent Document 2. As shown in FIG. 18, in the microwave oven 200, the microwave generated by the magnetron 201 passes through the waveguide 202 and reaches the rotating antenna 203 of the waveguide structure.

The rotating antenna 203 has a radiation port 207 that radiates microwaves formed on one side thereof and a low-impedance portion 206 that is formed on the other three sides, as viewed from above. The microwave radiated from the radiation port 207 is supplied to the heating chamber 204 via the power supply chamber 209, and the object to be heated placed in the heating chamber 204 is heated by microwaves.

The microwave oven disclosed in Patent Document 2 has an infrared sensor 210 for detecting a temperature distribution in the heating chamber 204. The control unit 211 controls the rotation and position of the rotating antenna 203 and the direction of the radiation port 207 based on the temperature distribution detected by the infrared sensor 210.

The rotary antenna 203 disclosed in Patent Document 2 is configured to move on an arcuate orbit while rotating inside the power supply chamber 209 formed below the mounting table 208 of the heating chamber 204 by the motor 205. According to the microwave oven 200, the radiation port 207 of the rotating antenna 203 can be rotated and moved to collectively heat the low temperature portion of the object to be heated detected by the infrared sensor 210.

Summary of invention

In the microwave oven 100 disclosed in Patent Document 1, the rotary antenna 103 is configured to rotate around the coupling shaft 109 disposed below the mounting table 108. The microwave is radiated from the radiation port 107 at the front end of the rotating antenna 103.

According to this configuration, the object to be heated placed in the central portion of the mounting table 108 cannot directly irradiate the microwave, and uniform heating is not necessarily achieved.

According to the microwave oven 200 disclosed in Patent Document 2, uniform heating and local heating of the object to be heated are possible. However, in this configuration, it is necessary to have a mechanism for moving the rotary antenna 203 while rotating under the mounting table 208, and the structure is complicated and the size of the device is increased.

The purpose of the present disclosure has been made to solve the above conventional problems, and an object thereof is to provide a microwave heating apparatus which has a simpler structure and can perform uniform heating and local heating.

A microwave heating apparatus according to an aspect of the present invention includes: a heating chamber for accommodating an object to be heated; a microwave generating unit for generating microwaves; and a waveguide structure antenna having a top surface and a side wall surface defining a waveguide structure portion, and a front opening And radiating microwaves from the front opening to the heating chamber. The waveguide structure portion has a coupling portion that engages with the top surface and couples the microwave to the internal space of the waveguide structure portion.

The waveguide structure has at least one microwave aspiration opening formed in the top surface and radiates circularly polarized waves from the microwave aspiration opening into the heating chamber. At least one of the microwave aspiration openings includes at least one pair of microwave aspiration openings that are symmetrical about the tube axis of the waveguide configuration. The waveguide structure portion has a flat region between the pair of microwave suction openings.

According to this aspect, it is possible to uniformly heat and locally heat the object to be heated placed in the heating chamber.

1,100,200‧‧‧ microwave oven

2a, 104, 204‧‧‧ heating room

2b, 209‧‧‧electric room

2c‧‧‧ to the side wall of the electric room

3, 101, 201‧‧ ‧ magnetron

3a‧‧‧The antenna of the magnetron

4, 102, 202, 300, 400, 500‧‧‧ guided wave tube

5,103, 203‧‧‧Rotating antenna

6, 108, 208‧‧‧ mounting platform

6a‧‧‧Loading surface

7‧‧‧Coupling Department

7a, 109‧‧‧ coupling shaft

7b‧‧‧Flange

8, 600, 700, 800, 900A, 900B, 38‧‧‧guide tube structure

9, 29, 39‧‧‧ top

9a, 909a‧‧‧ recess

2c, 10a, 10b, 10c‧‧‧ side wall

11‧‧‧ bottom

12, 106, 206‧‧‧ Low impedance section

12a, 20a, 20b, 20c, 20d, 20e, 20f‧‧‧ slits

13‧‧‧ front opening

14, 24, 34‧‧‧ microwave suction opening

14a, 24a, 34a, 614a, 714a, 814a, 914a‧ ‧ first opening

14b, 614b, 714b, 814b‧‧‧ second opening

15, 105, 205‧‧ ‧ motor

16, 210‧‧‧ Infrared sensor

17, 211‧‧‧Control Department

18, 18a, 18b‧‧‧ convex

19‧‧‧ Keeping Department

22‧‧‧heated objects

107, 207‧‧‧radiation

301‧‧‧ wide side

302‧‧‧Narrow side

303‧‧‧ profile

401, 501‧‧‧ openings

A‧‧‧width

B‧‧‧ Height

A‧‧‧1st length

B‧‧‧2nd length

C‧‧‧3rd length

D‧‧‧4th length

D, D1, D2, D3, D4, L1, L2‧‧‧ distance

E‧‧‧1st width

F‧‧‧2nd width

C1, C2, C3, C4‧‧ corner

G‧‧‧ Rotation Center

J‧‧‧ center line

K1, K2‧‧‧ plates

Ls, H‧‧‧ length

Center point of the first opening of P1‧‧

Center point of the second opening of P2‧‧

V‧‧‧ tube axis

W‧‧‧Width direction

X, Y‧‧‧ slit and tube axis distance

Z‧‧‧Microwave transmission direction

Fig. 1 is a cross-sectional view showing a schematic configuration of a microwave heating apparatus according to an embodiment of the present disclosure.

Fig. 2A is a view showing a power supply room in the microwave heating apparatus of the embodiment; Stereo picture.

Fig. 2B is a plan view showing a power supply chamber in the microwave heating apparatus of the embodiment.

Fig. 3 is an exploded perspective view showing the rotary antenna in the microwave heating apparatus of the embodiment.

Fig. 4 is a perspective view showing a general square waveguide.

Fig. 5A is a plan view showing a H-plane of a waveguide having an opening of a rectangular groove shape of a radiation linearly polarized wave.

Fig. 5B is a plan view showing a H-plane of a waveguide of an opening having a cross-shaped groove shape radiating a circularly polarized wave.

Fig. 5C is a front elevational view showing the positional relationship between the waveguide and the object to be heated.

Fig. 6A is a characteristic diagram showing experimental results in the case of the waveguide shown in Fig. 5A.

Fig. 6B is a characteristic diagram showing experimental results in the case of the waveguide shown in Fig. 5B.

Fig. 7 is a characteristic diagram showing experimental results in the case of "loading".

Fig. 8A is a cross-sectional view schematically showing an effect of sucking out in the embodiment.

Fig. 8B is a cross-sectional view schematically showing the suction effect in the embodiment.

Fig. 9A is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 9B is a schematic view showing a planar shape of an example of a rotating antenna used in the experiment.

Fig. 9C is a schematic view showing a planar shape of an example of a rotating antenna used in the experiment.

Fig. 10A is a schematic view showing a planar shape of an example of a rotating antenna used in an experiment.

Fig. 10B is a schematic view showing a planar shape of an example of a rotating antenna used in the experiment.

Fig. 11A is a plan view showing a waveguide structure portion of the embodiment.

Fig. 11B is a plan view showing a modification of the waveguide structure portion of the embodiment.

Fig. 12 is a view showing the arrangement of the intervals of the two-disc heated objects.

Fig. 13 is a view showing the abutting arrangement of the two-disc heated object.

Fig. 14 is a view showing the positions of respective portions of the microwave suction opening shown in Fig. 11B.

Figure 15 is a graph showing the results of the experiment.

Fig. 16A is a plan view showing a modification of the waveguide structure portion of the embodiment.

Fig. 16B is a plan view showing another modification of the waveguide structure portion of the embodiment.

Fig. 17 is a front sectional view showing the microwave oven disclosed in Patent Document 1.

Fig. 18 is a front sectional view showing the microwave oven disclosed in Patent Document 2.

Form for implementing the invention

A microwave heating apparatus according to a first aspect of the present invention includes: a heating chamber that houses an object to be heated; a microwave generating unit that generates microwaves; and a waveguide structure The antenna includes a top surface and a side wall surface of the predetermined waveguide structure portion, and a front opening, and radiates microwaves from the front opening to the heating chamber. The waveguide structure portion has a coupling portion that engages with the top surface and couples the microwave to the internal space of the waveguide structure portion.

The waveguide structure has at least one microwave aspiration opening formed in the top surface and radiates circularly polarized waves from the microwave aspiration opening into the heating chamber. At least one of the microwave aspiration openings includes at least one pair of microwave aspiration openings that are symmetrical about the tube axis of the waveguide configuration. The waveguide structure portion has a flat region between the pair of microwave suction openings.

According to this aspect, it becomes possible to uniformly heat and locally heat the object to be heated placed in the heating chamber.

According to the microwave heating apparatus of the second aspect, in the first aspect, the at least one microwave suction opening includes two pairs of microwave suction openings symmetrical with respect to the tube axis of the waveguide structure portion. Among the two pairs of microwave suction openings, the distance between the pair of openings closer to the coupling portion is longer than the distance between the pair of openings away from the coupling portion. According to this aspect, it becomes possible to more reliably emit a circularly polarized wave from the microwave suction opening.

According to the microwave heating apparatus of the third aspect, in addition to the second aspect, a driving unit that rotates the waveguide structure antenna is further provided. The coupling portion has a coupling shaft and a flange coupled to the driving portion and includes a rotation center of the waveguide structure antenna, the flange being disposed around the coupling shaft and constituting the joint portion. A pair of microwave suction openings that are closer to the coupling portion are disposed near the edge of the joint portion.

With this aspect, it becomes possible to heat the bearing more uniformly. The object to be heated in the central area of the surface.

According to the microwave heating apparatus of the fourth aspect, in the third aspect, the distance between the pair of microwave suction openings is substantially 1/8 to 1/4 of the width of the waveguide structure portion. By this aspect, the directivity of local heating can be improved.

Hereinafter, preferred embodiments of the microwave heating apparatus of the present disclosure will be described with reference to the accompanying drawings.

In the following embodiments, a microwave oven is used as an example of the microwave heating apparatus of the present disclosure. However, the present invention is not limited thereto, and includes a heating device using microwave heating, a kitchen processing machine, or a semiconductor manufacturing device. The present disclosure is not limited to the specific configuration shown in the following embodiments, and includes a configuration based on the same technical idea.

In the following drawings, the same reference numerals will be given to the same or equivalent parts, and the description of the repeated description will be omitted.

Fig. 1 is a front cross-sectional view showing a schematic configuration of a microwave oven of a microwave heating apparatus according to an embodiment of the present disclosure. In the following description, the left-right direction of the microwave oven means the left-right direction in FIG. 1, and the front-back direction means the depth direction in FIG.

As shown in Fig. 1, the microwave oven 1 of the present embodiment includes a heating chamber 2a, a power supply chamber 2b, a magnetron 3, a waveguide 4, a rotating antenna 5, and a mounting table 6. The mounting table 6 has a flat upper surface on which an object to be heated (not shown) for placing food or the like is placed. The heating chamber 2a is a space above the mounting table 6, and the power feeding chamber 2b is a space below the mounting table 6.

The mounting table 6 covers the power supply chamber 2b provided with the rotating antenna 5, and partitions the heating chamber 2a and the power feeding chamber 2b to constitute the bottom surface of the heating chamber 2a. Due to Since the upper surface (mounting surface 6a) of the mounting table 6 is flat, it is easy to make in and out of the object to be heated, and the dirt or the like adhering to the mounting surface 6a can be easily wiped off.

Since the mounting table 6 is made of a material that is easily penetrated by microwaves such as glass or ceramics, the microwave radiated from the rotating antenna 5 can be supplied to the heating chamber 2a through the mounting table 6.

The magnetron 3 is an example of a microwave generating unit that generates microwaves. The waveguide 4 is disposed below the power supply chamber 2b and is an example of a transmission portion that propagates the microwave generated by the magnetron 3 to the coupling portion 7. The rotating antenna 5 is disposed in the internal space of the power feeding chamber 2b, and radiates microwaves propagating through the waveguide 4 and the coupling portion from the front opening 13 into the power feeding chamber 2b.

The rotating antenna 5 is a waveguide structure antenna having a waveguide structure portion 8 and a coupling portion 7, and the waveguide structure portion 8 has a box-shaped waveguide structure that transmits microwaves in its internal space, and the coupling portion 7 makes The microwaves in the waveguide 4 are coupled to the internal space of the waveguide structure portion 8. The coupling portion 7 has a coupling shaft 7a coupled to the driving portion (ie, the motor 15), and a flange 7b that engages the waveguide structure portion 8 and the coupling portion 7.

The motor 15 is driven in response to a control signal from the control unit 17 so that the rotary antenna 5 rotates around the coupling shaft 7a of the coupling portion 7 and stops it in a desired direction. Thereby, the radiation direction of the microwave from the rotating antenna 5 can be changed. The coupling portion 7 is made of a metal such as an aluminum-plated steel sheet, and the connecting portion of the motor 15 coupled to the coupling portion 7 is made of, for example, a fluororesin.

The coupling shaft 7a of the coupling portion 7 penetrates through the opening of the communication waveguide 4 and the power supply chamber 2b, and the coupling shaft 7a has a predetermined gap (for example, 5 mm or more) between the opening and the through hole. The waveguide 4 can be rotated by the coupling shaft 7a The internal space of the waveguide structure portion 8 of the antenna 5 is coupled, and the microwaves are efficiently transmitted from the waveguide 4 to the waveguide structure portion 8.

An infrared sensor 16 is disposed on an upper portion of the side of the heating chamber 2a. The infrared sensor 16 is an example of a state detecting unit that detects the temperature in the heating chamber 2a (that is, the surface temperature of the object to be heated placed on the mounting table 6) as the object to be heated. The infrared sensor 16 detects the temperature of each region of the plurality of heating chambers 2a that is virtually divided into a plurality, and transmits the detection signals to the control unit 17.

The control unit 17 performs the oscillation control of the magnetron 3 and the drive control of the motor 15 based on the detection signal of the infrared sensor 16.

In the embodiment of the present embodiment, the infrared sensor 16 is provided as an example of the state detecting unit, but the state detecting unit is not limited thereto. For example, a weight sensor that detects the weight of the object to be heated, an image sensor that captures an image of the object to be heated, or the like may be used as the state detecting side portion. In the configuration in which the state detecting unit is not provided, the control unit 17 may perform the oscillation control of the magnetron 3 and the drive control of the motor 15 in accordance with the program stored in advance and the user's selection.

FIG. 2A is a perspective view showing the power supply chamber 2b in a state where the mounting table 6 is removed. Fig. 2B is a plan view showing the power supply chamber 2b in the same state as Fig. 2A.

As shown in FIG. 2A and FIG. 2B, a rotating antenna 5 is provided in the power supply chamber 2b disposed below the heating chamber 2a and separated from the heating chamber 2a by the mounting table 6. The center of rotation G of the coupling shaft 7a of the rotating antenna 5 is located in the front and rear directions of the power feeding chamber 2b and the center in the left-right direction, that is, before the mounting table 6. Below the center of the direction and left and right direction.

The power supply chamber 2b has an internal space formed by the bottom surface 11 and the lower surface of the mounting table 6. The internal space of the power supply chamber 2b includes the rotation center G of the coupling portion 7, and has a symmetrical shape with respect to the center line J (refer to FIG. 2B) in the left-right direction of the power supply chamber 2b. A convex portion 18 that protrudes inward is formed on a side wall surface of the internal space of the power supply chamber 2b. The convex portion 18 includes a convex portion 18a provided on the left side wall surface and a convex portion 18b provided on the right side wall surface.

A magnetron 3 is disposed below the convex portion 18b. The microwave radiated from the antenna 3a of the magnetron 3 is transmitted through the waveguide 4 disposed below the power supply chamber 2b, and propagates to the waveguide structure portion 8 by the coupling portion 7.

The side wall surface 2c of the power feeding chamber 2b has an inclination for reflecting the microwave radiated by the rotating antenna 5 in the horizontal direction toward the upper heating chamber 2a.

FIG. 3 is an exploded perspective view showing a specific example of the rotating antenna 5. As shown in Fig. 3, the waveguide structure portion 8 has a top surface 9 and side wall surfaces 10a, 10b, and 10c defining an internal space thereof.

The top surface 9 includes three straight edge portions, one arcuate edge portion, and a concave portion 9a to which the coupling portion 7 is joined, and is provided to face the mounting table 6 (see FIG. 1). The three linear end portions of the top surface 9 are bent downward to form side wall surfaces 10a, 10b, and 10c, respectively.

A side wall surface is not provided on the arcuate edge portion, and an opening is formed below it. This opening functions as a front opening 13 for radiating microwaves transmitted in the internal space of the waveguide structure portion 8. That is, the side wall surface 10b is provided to face the front opening 13, and the side wall surfaces 10a, 10c are opposed to each other.

The lower edge portion of the side wall surface 10a is provided with a low-impedance portion 12 that is outside the waveguide structure portion 8 and extends in the vertical direction with respect to the side wall surface 10a. The low-impedance portion 12 is formed in parallel with the bottom surface 11 of the power supply chamber 2b with a slight gap therebetween. By the low-impedance portion 12, it is possible to suppress microwaves leaking in the vertical direction with respect to the side wall surface 10a.

In order to secure a fixed gap with the bottom surface 11 of the power supply chamber 2b, a holding portion 19 for mounting an insulating resin spacer (not shown) may be formed on the lower surface of the low-impedance portion 12.

In the low-impedance portion 12, a plurality of slits 12a are provided to periodically extend from the side wall surface 10a in the vertical direction at regular intervals. By the plurality of slits 12a, leakage of microwaves in a direction parallel to the side wall surface 10a can be suppressed. The interval between the slits 12a can be appropriately determined in accordance with the wavelength transmitted in the waveguide structure portion 8.

Similarly, in the side wall surface 10b and the side wall surface 10c, the low-impedance portion 12 having a plurality of slits 12a is provided in each of the lower edge portions.

The rotating antenna 5 of the present embodiment has the arc-shaped front opening 13 formed therein. However, the present disclosure is not limited to this shape, and may have a linear or curved front opening 13.

As shown in FIG. 3, the top surface 9 includes a plurality of microwave suction openings 14, that is, a first opening 14a and a second opening 14b having an opening smaller than the first opening 14a. The microwaves transmitted in the internal space of the waveguide structure portion 8 are radiated from the front opening 13 and the plurality of microwave suction openings 14.

The flange 7b formed on the coupling portion 7 is on the lower surface of the top surface 9 of the waveguide structure portion 8, for example, riveting, spot welding, screw fastening, or borrowing It is joined by welding or the like to fix the rotating antenna 5 and the coupling portion 7.

In the present embodiment, since the rotating antenna 5 has the waveguide structure 8 as will be described later, it is possible to form uniform heating of the object to be placed placed on the mounting table 6. In particular, it is possible to efficiently and uniformly heat the central portion of the mounting surface 6a located above the rotation center G (see FIGS. 2A and 2B) of the rotating antenna 5. Hereinafter, the structure of the waveguide of the present embodiment will be described in detail.

[guide tube structure]

First, in order to understand the characteristics of the waveguide structure portion 8, a general waveguide 300 will be described using FIG. As shown in FIG. 4, the most simple and general waveguide 300 is a square waveguide having a rectangular section 303 having a width a and a height b, and a tube axis V along the waveguide 300. The depth. The tube axis V is the center line of the waveguide tube 300 that passes through the center of the section 303 and extends in the direction of propagation of the microwaves Z.

It is known that when the wavelength of the microwave in the free space is λ ₀ , if the width a and the height b are selected from the range of λ ₀ > a > λ ₀ / 2, and b < λ ₀ /2, The microwaves are transmitted in the waveguide 10 in the TE10 mode.

The TE10 mode refers to a transmission mode in an H-wave (TE wave; Transverse Electric Wave) in which a magnetic field component exists but there is no electric field component in the transmission direction Z of the microwave in the waveguide 300.

The wavelength λ ₀ of the microwave in the free space can be obtained by the equation (1).

[Number 1] λ ₀ = c / f... (1)

In the formula (1), the speed of light c is about 2.998 × 10 ⁸ [m/s], and the oscillation frequency f is 2.4 to 2.5 [GHz] (ISM band) in the case of a microwave oven. Since the oscillation frequency f varies due to inconsistencies or load conditions of the magnetron, the wavelength λ ₀ in free space will be between a minimum of 120 [mm] (2.5 GHz) and a maximum of 125 [mm] (2.4 GHz). change.

In the case of the microwave tube 300 used in the microwave oven, the width a of the waveguide 300 is usually in the range of 80 to 100 mm and the height b is in the range of 15 to 40 mm in consideration of the range of the wavelength λ ₀ in the free space. Design.

In general, in the waveguide 300 shown in Fig. 4, the broad side surface 301 of the upper surface and the lower surface is referred to as the H surface in the sense that the magnetic field is rotated in parallel, and is parallel to the electric field. In the sense, the narrow side faces 302 on the left and right sides are referred to as E faces. For the sake of simplicity, in the plan view shown below, a straight line projecting the tube axis V onto the H surface on the H surface is sometimes referred to as a tube axis V.

When the wavelength of the microwave from the magnetron are predetermined for the λ _0, when the wavelength of the microwave and pass within the waveguide wavelength λ _g within the predetermined tube and to be represented by the formula (2) is obtained by λ _g.

Therefore, the in-tube wavelength λ _g varies depending on the width a of the waveguide 300, but has no relationship with the height b. In the TE10 mode, both ends (E plane) of the width direction W of the waveguide 300 mean that the electric field at the narrow side surface 302 is 0, and the electric field is maximum at the center of the width direction W.

In the present embodiment, the same principle as that of the waveguide 300 shown in Fig. 4 is applied to the rotating antenna 5 shown in Figs. 1 and 3 . In the rotary antenna 5, the top surface 9 and the bottom surface 11 of the power supply chamber 2b are H faces, and the side wall surfaces 10a and 10c are E faces.

The side wall surface 10b is a reflection end for reflecting all of the microwaves in the rotating antenna 5 in the direction of the front opening 13. In the present embodiment, specifically, the width a of the waveguide 300 is 106.5 mm.

A plurality of microwave suction openings 14 are formed in the top surface 9. The microwave suction opening 14 includes two first openings 14a and two second openings 14b. The two first openings 14a are symmetrical with respect to the tube axis V of the waveguide structure portion 8 of the rotating antenna 5. Similarly, the two second openings 14b are symmetrical with respect to the tube axis V. The first opening 14a and the second opening 14b are formed so as not to cross the tube axis V.

By arranging the first opening 14a and the second opening 14b at a position away from the tube axis V of the waveguide structure portion 8 (correctly, a line projecting the tube axis V onto the top surface 9 of the top surface 9) With the configuration, the circular polarization wave can be more reliably radiated by the microwave suction opening 14. By radiating the microwave of the circularly polarized wave, uniform heating of the central region of the mounting surface 6a can be formed.

Further, the first opening 14a and the second opening 14b may be provided in any one of the left and right of the tube axis V to determine the direction of rotation of the electric field, that is, a right-handed polarized wave (CW: Clockwise) or a left-handed pole. Wave (CCW: Counterclockwise).

In the present embodiment, each of the microwave suction openings 14 is provided so as not to cross the tube axis V. However, the present disclosure is not limited thereto, and even in a configuration in which one of the openings is a portion spanning the tube axis V, it is possible to emit a circularly polarized wave. At this time, a deformed circularly polarized wave is generated.

[circular polarized wave]

Next, the circularly polarized wave will be described. Circularly polarized waves are widely used in the fields of mobile communication and satellite communication. As a cut Examples of the use of the body include, for example, an ETC (Electronic Toll Collection System), that is, an automatic toll collection system.

The circularly polarized wave is a microwave in which the polarization plane of the electric field rotates with respect to the traveling direction in response to the time, and the direction of the electric field continuously changes according to the time, and the magnitude of the electric field strength does not change.

As long as the circularly polarized wave is applied to the microwave heating apparatus, it is expected that the object to be heated is uniformly heated in comparison with the microwave heating formed by the conventional linearly polarized wave, particularly in the circumferential direction of the circularly polarized wave. Furthermore, the same effect can be obtained regardless of which of the right-handed polarized wave and the left-handed polarized wave.

Circularly polarized waves are mainly used in the field of communication, and since radiation to the open space is targeted, it is generally discussed as a so-called traveling wave without reflected waves. On the other hand, in the present embodiment, a reflected wave is generated in the heating chamber 2a in the closed space, and the generated reflected wave and the traveling wave are combined to generate a standing wave.

However, in addition to reducing the reflected wave by the microwave absorption of the food, it is also conceivable that the equilibrium of the standing wave is collapsed at the moment when the microwave is radiated from the opening 14 by the microwave, and the travel can be generated in the time before the standing wave is generated again. wave. Therefore, according to the present embodiment, the uniform heating in the heating chamber 2a can be formed by utilizing the characteristics of the circularly polarized wave described above.

Here, the areas of communication in an open space and the differences in the field of dielectric heating in an enclosed space are described.

In the field of communication, one of the right-handed polarized wave or the left-handed polarized wave is used for the transmission and reception of the exact information. On the receiving side, What is used is a receiving antenna that has a directivity suitable for it.

On the other hand, in the field of microwave heating, since the receiving object having directivity is replaced by a receiving antenna having directivity, it is important to irradiate the entire object to be heated with microwaves. Therefore, in the field of microwave heating, it is not important that the right-handed polarized wave or the left-handed polarized wave is present, and there is no problem even in a state in which the right-handed polarized wave and the left-handed polarized wave are mixed.

[Microwave suction effect]

Here, the feature of the present embodiment (that is, the suction effect of the microwave from the rotating antenna) will be described. In the present embodiment, the microwave suctioning effect means that the microwave in the waveguide structure is sucked by the microwave suction opening 14 when there is a heated object such as a food in the vicinity.

Fig. 5A is a plan view of a waveguide 400 having a H-face provided with an opening for generating a linearly polarized wave. Fig. 5B is a plan view of a waveguide 500 having a H-face provided with an opening for generating a circularly polarized wave. Fig. 5C is a front elevational view showing the positional relationship between the waveguide 400 or 500 and the object 22 to be heated.

As shown in FIG. 5A, the opening 401 is a rectangular slit that is disposed to intersect the tube axis V of the waveguide 400. The opening 401 emits microwaves of linearly polarized waves. As shown in FIG. 5B, the two openings 501 are openings of a cross slot shape formed by two rectangular slits intersecting at right angles. The two openings 501 are symmetrical with respect to the tube axis V of the waveguide 500.

Regardless of which opening, it is symmetrical with respect to the tube axis V of the waveguide, and has a width of 10 mm and a length of Lmm. In these configurations, When the "no load" of the object 22 to be heated and the "loading" of the object 22 to be heated were not disposed, the analysis was performed using CAE.

When there is "loading", as shown in Fig. 5C, the height of the fixed object 22 is 30 mm, the bottom areas of the two kinds of objects 22 (100 mm angle, 200 mm angle), and the materials of the three objects to be heated 22. In the (frozen beef, chilled beef, and water), the distance D from the waveguides 400 and 500 to the bottom surface of the object 22 to be heated was measured as a parameter.

In order to use the radiation power from the opening in the case of "no load" as a reference, the relationship between the length of the opening and the radiation power in the case of "no load" is shown in FIGS. 6A and 6B.

Fig. 6A is a characteristic showing the case of the opening 401 shown in Fig. 5A, and Fig. 6B is a characteristic showing the case of the opening 501 shown in Fig. 5B. In FIGS. 6A and 6B, the horizontal axis is the length L [mm] of the opening, and the vertical axis is the electric power of the microwaves radiated by the openings 401, 501 when the electric power transmitted in the waveguide is 1.0 W. ].

In the case of "no load", the radiation power is set to a length L of 0.1 W, that is, in the graph shown in FIG. 6A, the length L is selected to be 45.5 mm. In the graph shown in Fig. 6B, the case where the length L is selected to be 46.5 mm is selected.

Fig. 7 includes six graphs showing three types of bottom areas (100 mm angle, 200 mm angle) in the case where the length L is the above length (45.5 mm, 46.5 mm) and "loaded". Analytical results of food (frozen beef, chilled beef, water).

In each of the graphs included in Fig. 7, the horizontal axis is from the object 22 to be heated. The distance D [mm] from the waveguide, and the vertical axis is the relative radiation power when the radiation power at the time of "no load" is 1.0. That is, what is shown is how much microwaves can be drawn by the waveguides 400, 500 in the case of "loading" compared to the case of "no load".

In each of the graphs shown in Fig. 7, the broken line indicates the characteristic of the opening 401 of the straight line shape (I-shape) (indicated by "I" in the figure), and the solid line indicates the shape of two cross grooves (X shape). The characteristic of the case of the opening 501 (indicated by "2X" in the figure).

Regardless of which of the six charts, the opening 501 has a larger amount of radiated power than the opening 401, and in particular, in the case where the distance D is 20 mm or less and the same distance as in the case of the actual microwave oven, it can be understood that there are 2 times. The difference between left and right. Therefore, it has become apparent that regardless of the kind or the bottom area of the object 22 to be heated, the microwave suction effect of the opening which causes the circularly polarized wave is higher than that of the opening which causes the linearly polarized wave to be generated.

As will be understood in detail, the type of the object to be heated 22, particularly when the distance D is 10 mm or less, has a large absorption effect of the frozen beef having a small dielectric constant and dielectric loss, and a dielectric constant and a dielectric constant. The water with a large loss has a small suction effect.

In the case of chilled beef or water, when the distance D becomes large, particularly a linearly polarized wave, the radiation power is lowered to 1 or less. The reason for this is considered to be that the radiation power is offset by the reflected electric power from the object 22 to be heated. Regarding the bottom area of the object 22 to be heated, since the radiation power is almost the same at the angle of 100 mm and the angle of 200 mm, it is considered that the effect on the suction effect of the microwave is small.

The inventors have explored the conditions under which openings of circularly polarized waves can be radiated by experiments using various opening shapes. The result is as follows. Preferred conditions for generating a circularly polarized wave include: arranging the opening away from the tube axis V of the waveguide, and opening the opening in the shape of a cross groove. The condition that the microwave of the circularly polarized wave is most efficiently radiated, that is, the condition that the suction effect is high, is an opening having a cross groove shape.

8A and 8B are cross-sectional views schematically showing the suction effect in the embodiment. The front opening 13 of the rotating antenna 5 is directed to the left direction in the drawing in both FIGS. 8A and 8B. The object to be heated 22 is disposed above the coupling portion 7 in Fig. 8A, and is placed on the left corner of the mounting surface 6a in Fig. 8B. That is, in the two states shown in FIGS. 8A and 8B, the distance from the coupling portion 7 to the object 22 to be heated is different.

In the state shown in FIG. 8A, it is conceivable that the object to be heated 22 approaches the microwave suction opening 14, in particular, the first opening 14a, and the suction effect from the first opening 14a is generated. As a result, most of the microwaves that travel through the coupling portion 7 toward the front opening 13 are radiated from the first opening 14a into the microwave of the circularly polarized wave, and the object 22 is heated to heat the object 22 to be heated.

On the other hand, in the state shown in FIG. 8B, since the object 22 to be heated is away from the microwave suction opening 14, it is considered that the suction effect from the microwave suction opening 14 is less likely to occur. As a result, the microwave that has traveled most of the forward portion 13 by the coupling portion 7 causes the microwave of the linearly polarized wave to be radiated from the front opening 13 to the object 22 to be heated, and the object 22 to be heated is heated.

As described above, it is conceivable to open the microwave by the present embodiment. The mouth 14 causes a special phenomenon in which the radiation power is increased when the food is placed close to the microwave suction opening 14, and the radiation power is reduced when the food is disposed at a position away from the microwave suction opening 14.

[Uniform heating formed by the waveguide structure section]

Hereinafter, the uniform heating formed by the waveguide structure portion of the present embodiment will be described. The inventors conducted experiments using a rotating antenna having a waveguide structure of various shapes, and found a waveguide structure that is most suitable for uniform heating.

9A, 9B, and 9C are schematic views each showing a planar shape of three examples of the rotating antenna used in the experiment.

As shown in FIG. 9A, the waveguide structure portion 600 has two first openings 614a and two second openings 614b. The first opening 614 a has a cross groove shape, and each rectangular slit is provided in the vicinity of the coupling portion 7 so as to form an angle of 45 degrees with respect to the tube axis V of the waveguide structure portion 600 . The second opening 614b is smaller than the first opening 614a and is provided farther from the coupling portion 7.

As shown in FIG. 9B, the waveguide structure portion 700 has a first opening 714a different from the waveguide structure portion 600, and the first opening 714a has a cross groove shape similar to that of the first opening 614a.

As shown in FIG. 9C, the waveguide structure portion 800 is different from the waveguide structure portion 600, and includes two first openings 814a having a T shape. In other words, unlike the first opening 614a, the first opening 814a does not have a portion extending from the intersecting portion toward the coupling portion 7 on one side of the two rectangular slits.

The waveguide structure portion shown in FIGS. 9A to 9C is common in that a microwave suction opening having a plurality of cross-shaped groove shapes is provided, and the same size is used. The first opening is provided in the same place, and the second opening of the same size is placed in the same place. In particular, the second opening 614b, the second opening 714b, and the second opening 814b are the same.

The rotating antenna having the waveguide structure shown in FIGS. 9A to 9C was used, and the experiment was carried out under the same heating conditions using the frozen Osaka-fired material placed on the central portion of the mounting surface 6a, and verified by CAE. The so-called Osaka-style roast is a pancake-shaped dish made of batter containing various materials.

In the case of the waveguide structure portion 600 shown in FIG. 9A, it is understood that the circularly polarized waves outputted from the openings form interference, and the central region of the mounting surface 6a above the coupling portion 7 is formed. The temperature of the portion of the object to be heated is abnormally unable to rise as compared with the portion around it (hereinafter, the temperature in the vicinity of the coupling portion 7 is lowered).

In the case of the waveguide structure portion 700 shown in FIG. 9B, the temperature drop in the vicinity of the coupling portion 7 can be suppressed. In the case of the waveguide structure portion 800 shown in FIG. 9C, similarly, the temperature in the vicinity of the coupling portion 7 can be suppressed from being lowered.

As described above, it can be confirmed that the opening is not provided in the vicinity of the coupling portion 7, or the waveguide structure is provided with only one opening in the vicinity of the coupling portion 7, and the temperature in the vicinity of the coupling portion 7 can be suppressed from being lowered. Uniform heating in the heating chamber 2a.

Further, the inventors conducted experiments on the shape of the microwave suction opening, and found a waveguide structure which can make the heating distribution more uniform.

According to the first opening of the waveguide structure portion 800 shown in FIG. 9C 814a, since it is a circular circularly polarized wave formed by the opening of the shape of the cross groove, it can be said that it is a deformed circularly polarized wave, and therefore, from the viewpoint of uniform heating in the heating chamber 2a, Unable to get better results.

Then, in order to suppress the interference of the two circularly polarized waves and to form a circularly polarized wave close to a circular shape as much as possible, the first opening 914a having the shape shown in Figs. 10A and 10B was examined.

Hereinafter, the waveguide structure portion having the first opening 914a will be described in detail with reference to the drawings.

FIGS. 10A and 10B are schematic diagrams each showing a planar shape of the waveguide structure portion 900A and the waveguide structure portion 900B in which the first opening 914a is provided.

As shown in FIGS. 10A and 10B, the waveguide structure portions 900A and 900B each have the same first opening 914a and second opening 914b.

The first opening 914a has a cross groove shape in which a portion extending from the intersection portion toward the coupling portion 7 on one side of the two rectangular slits has a shorter portion than a portion extending from the intersection portion in the opposite direction to the coupling portion 7. length. As a result of the investigation, it was confirmed that the uniform heating was possible in addition to the interference of the two circularly polarized waves in accordance with the first opening 914a, compared with the first opening 814a shown in Fig. 9C. The aforementioned suction effect is also made high.

The length of the portion of the first opening 914a extending from the intersecting portion toward the coupling portion 7 is appropriately set in accordance with the specifications so that the interference of the two circularly polarized waves does not occur.

The waveguide structure portion 900A has an overall flat top surface. On the other hand, the waveguide structure portion 900B forms a concave joint region (a recess portion 909a of the drop region) which is recessed downward in the joint portion where the flange 7b is joined to the top surface (see, for example, FIG. 3). Therefore, in the top surface of the waveguide structure 900B, the distance between the joint region and the mounting table is longer than that of the other portions.

A rotating antenna having the above-described waveguide structure portion was used, and similarly, the experiment was carried out under the same heating conditions using the frozen Osaka-fired ceramic placed on the central portion of the mounting surface 6a, and verified by CAE.

As a result, since the first opening 914a has a substantially cross-shaped groove shape, the waveguide structure portion 900A can suppress the interference of the two circularly polarized waves and generate a circularly polarized wave that is close to the shape of a circle.

Moreover, the suction effect is increased by the first opening 914a, and the temperature drop in the vicinity of the coupling portion 7 can be suppressed. Further, it is also known that the temperature in the vicinity of the coupling portion 7 can be suppressed from being lowered by the concave joint region formed on the top surface of the waveguide structure portion 900B.

[guide tube structure portion of the present embodiment]

Hereinafter, a rotating antenna according to the present embodiment, which is based on the findings of various experiments as described above, will be described. In the present embodiment, an example of a specific configuration is shown, and various modifications can be made in accordance with the specifications of the microwave heating device and the like based on the above findings.

Fig. 11A is a plan view showing a rotary antenna having a waveguide structure portion 8 of the embodiment.

As shown in FIG. 11A, the waveguide structure portion 8 has a plurality of microwave suction openings 14 provided on the top surface 9. A plurality of microwave suction openings 14 include: The first opening 14a and the second opening 14b having an opening smaller than the first opening 14a. The first opening 14a and the second opening 14b have substantially a cross groove shape.

By arranging the center point P1 of the first opening 14a and the center point P2 of the second opening 14b at a position deviating from the position of the tube axis V of the waveguide structure portion 8, the microwave suction opening 14 can emit circularly polarized waves. . Here, the center point P1 of the first opening 14a and the center point P2 of the second opening 14b are the center points of the intersection regions of the two slits forming the first opening 14a and the second opening 14b, respectively.

In the present embodiment, the first opening 14a and the second opening 14b are disposed so as not to cross the tube axis V of the waveguide tube forming portion 8. The longitudinal direction of each of the rectangular slits of the first opening 14a and the second opening 14b is substantially inclined at 45 ° C with respect to the tube axis V.

As shown in FIG. 11A, the first opening 14a is formed to be close to the concave portion 9a of the top surface 9. The recessed portion 9a is a drop region (see FIG. 3) that is provided so as to protrude from the top surface 9 in a direction (downward direction) opposite to the traveling direction of the microwave radiated by the first opening 14a. The two first openings 14a are symmetrical with respect to the tube axis V.

The second opening 14b is formed in the vicinity of the front opening 13 away from the coupling portion 7 than the first opening 14a. Similarly to the first opening 14a, the two second openings 14b are symmetrical with respect to the tube axis V.

The first opening 14a has a feature in which the length of the portion extending from the center point P1 in the direction of the tube axis V is shorter than the length of the portion extending from the center point P1 toward the side wall surface 10a.

As shown in FIG. 3, the flange 7b provided in the coupling portion 7 has a shape in which the length in the microwave transfer direction Z is shorter than the length in the width direction W of the waveguide structure portion 8. That is, the coupling portion 7 is the length of the microwave transfer direction Z, It is shorter than the length in the direction orthogonal to the transport direction Z. According to the flange 7b, the front end of the slit extending from the center point P1 toward the coupling portion 7 can be formed closer to the coupling portion 7.

In the present embodiment, since the flange 7b is joined to the back side of the recessed portion 9a, it is compared with the flange 7b such as the protrusion of the TOX riveting, the weld mark, the screw, and the head of the nut. The height of the projection generated on the front side of the recess 9a is such that the recess 9a is made deeper. According to this embodiment, there is no problem that the projections come into contact with the lower surface of the mounting table 6.

The waveguide structure portion 8 shown in Fig. 11A has a concave portion 9a provided on the top surface 9 above the coupling portion 7, and has the same configuration as the waveguide structure portion 900B shown in Fig. 10B. According to the waveguide structure portion 8 shown in Fig. 11A, similarly to the waveguide structure portion 900B, the temperature drop in the vicinity of the coupling portion 7 can be suppressed. The reasons for this are considered to be the following two.

First, when the object to be heated is placed above the first opening 14a, a part of the microwave radiated by the first opening 14a and which becomes a circularly polarized wave is reflected on the object to be heated. The reflected microwaves are repeatedly reflected in the space formed between the upper surface of the concave portion 9a and the lower surface of the mounting table 6, and as a result, the object to be heated can be heated more strongly.

Second, in the present embodiment, the internal space of the waveguide structure portion 8 in which the concave portion 9a is formed is narrower than the other portions. The microwaves that are transmitted to the waveguide shaft structure portion 8 by the coupling shaft 7a are radiated by the first opening 14a by the suction effect when the narrow space near the concave portion 9a travels in a wide space away from the concave portion 9a. On the other hand, the object to be heated placed in the central portion of the mounting surface 6a is strongly heated.

Hereinafter, the shape of the first opening 14a of the present embodiment will be described in detail.

As shown in FIG. 11A, the first opening 14a includes slits 20a and 20b and has a cross groove shape such that the center point P1 intersects. The long axis of each slit of the first opening 14a has an angle of 45 degrees with respect to the tube axis V.

The slit 20a extends from the lower right to the upper left of the center point P1, and has a first length A from the center point P1 to the lower right end and a third length C from the center point P1 to the upper left end. The lower right end of the slit 20a approaches the concave portion 9a toward the coupling portion 7.

The slit 20b extends from the lower left to the upper right of the center point P1, and has a second length B from the center point P1 to the lower left end and a fourth length D from the center point P1 to the upper right end. That is, the first length A is the length from the center point P1 to the front end of the slits 20a and 20b and the length closest to the front end of the coupling portion 7.

The third length C is the same as the fourth length D, and these substantially correspond to 1/4 of the wavelength of the microwave transmitted in the waveguide structure portion 8. The second length B is shorter than the third length C and the fourth length D, and the first length A is the shortest among these.

Further, the distance X between the slit 20a and the tube axis V is longer than the distance Y between the slit 20b and the tube axis V. That is, among the two pairs of slits constituting the pair of microwave suction openings 14, the distance between the pair of slits 20a closer to the coupling portion 7 is larger than the distance between the pair of slits 20b far from the coupling portion 7. long. Therefore, the top surface 9 is such that the area in the vicinity of the concave portion 9a between the two first openings 14a is made wider than the area away from the concave portion 9a.

In the case where the area between the two first openings 14a is not flat, Since a turbulent electromagnetic field is generated in the waveguide structure portion 8 and adversely affects the formation of the circularly polarized wave, it is preferable to provide a relatively flat and flat between the two first openings 14a. region. According to the present embodiment, a circularly polarized wave having less turbulence can be formed by a relatively wide and flat region provided between the two first openings 14a, and a high suction effect can be obtained.

On the other hand, the second opening 14b has a cross groove shape in which two slits having the same length are orthogonal to each other at their respective centers. The long axis of each slit of the second opening 14b has an angle of 45 degrees with respect to the tube axis V. In the present embodiment, the length of the major axis of each slit of the second opening 14b is the same length as the third length C and the fourth length D of the first opening 14a.

The coupling portion 7 of the present embodiment has the flange 7b having the above-described shape, but the shape of the flange 7b is not limited thereto, and can be appropriately changed depending on the specifications.

For example, if the portion of the flange 7b in the direction of the tube axis V is shortened, the first opening 14a can be provided closer to the coupling portion 7. The flange 7b having a notch between the first opening 14a and the like may be used, and the first opening 14a may be provided closer to the coupling portion 7 by the shape of the flange 7b.

As long as the shape of the flange 7b is reduced, the joining of the coupling portion 7 and the waveguide structure portion 8 can be enhanced without reducing the area of the joint portion, and the inconsistency of the products can be suppressed.

When the coupling shaft 7a has a cross section such as a semicircle, an ellipse or a rectangle, or when the coupling shaft 7a having such a cross-sectional shape is directly joined to the waveguide structure portion 8, the same effects as those of the present embodiment can be obtained. According to the configuration in which the flange 7b is not provided, it can be further expanded to form the first opening. 14a space.

According to the present embodiment, since the temperature increase in the vicinity of the coupling portion 7 can be suppressed by obtaining a high suction effect, uniform heating in the central portion of the mounting surface 6a can be formed.

In the present embodiment, the microwave suction opening has a cross recess shape, but the microwave suction opening of the present disclosure is not limited thereto. The microwave suction opening may have a shape in which a circularly polarized wave can be generated in addition to the shape of the cross groove.

As a result of the experiment, it is presumed that a necessary condition for generating a circularly polarized wave by the waveguide structure portion is to arrange the two elongated openings at a position offset from the tube axis.

The slit constituting the microwave suction opening 14 is not limited to a rectangular shape. For example, in the case where there is a circular opening or an elliptical opening on the corner, a circularly polarized wave can also be generated.

On the contrary, in order to suppress the concentration of the electric field, it is preferable to have a circle with a rounded corner. In the present embodiment, as shown in FIGS. 3, 9A to 9C, 10A, 10B, and 11A, the slits included in the first opening 14a and the second opening 14b each have a circle at the front end and the intersecting portion. The corner. That is, the two slits included in the microwave suction opening 14 have a width near the intersection of the width wider than the end portion.

In the present embodiment, the concave portion 9a is formed above the coupling portion 7 of the top surface 9, but the waveguide structure portion 8 of the present disclosure is not limited thereto.

For example, it is also possible to consider between the microwave suction opening 14 and the rotation center of the waveguide structure portion 8 in consideration of the transmission state of the microwave radiated from the opening or the like. The recess 9a is provided. A convex portion that protrudes from the inner space of the waveguide structure portion 8 may be provided on the top surface 9 on the side closer to the rotation center of the waveguide structure portion 8 than the microwave suction opening 14.

That is, the waveguide structure portion 8 may have a drop region which is provided on a portion of the top surface 9 which is closer to the coupling portion 7 than the microwave suction opening 14 and which has a lower height than the other portions of the top surface 9.

[slit shape]

The inventors of the present invention have developed a highly reliable waveguide structure portion by creating the angular shape of the intersection of the two slits in the first opening 14a. This waveguide structure portion will be described using Fig. 11B.

As shown in FIG. 11B, the waveguide structure portion 28 of the present modification has a microwave suction opening 24 provided on the top surface 29. The microwave suction opening 24 includes a first opening 24a and a second opening 14b. As will be described below, the first opening 24a differs only in the angular shape of the intersection of the two slits of the first opening 24a shown in FIG. 11A.

As shown in FIG. 11B, the first opening 24a has four corners C1, C2, C3, and C4 at the intersection of the slit 20c and the slit 20d.

The angle C1 is located farthest from the tube axis V. The angle C2 is set on the most upstream side in the transmission direction Z of the microwave, and is located closest to the coupling portion 7. The angle C3 is located closest to the tube axis V. The angle C4 is set on the most downstream side in the microwave transmission direction Z, and is located farthest from the coupling portion 7.

Among the angles C1 to C4, the angles C1 to C3 have curved shapes having equal curvatures, and on the other hand, the angles C4 have curved shapes smaller than the angles C1 to C3. In the configuration shown in Fig. 11B, the angle C4 has a shape in which the portion indicated by the broken line in Fig. 11B is almost linearly cut.

The distance D1 is set as the distance from the center point P1 to the angle C1, the distance D2 is set as the distance from the center point P1 to the angle C2, and the distance D3 is set as the distance from the center point P1 to the angle C3, and the distance D1 to D3 It will be the same, and the distance D4 from the center point P1 to the angle C4 will be larger than the distances D1 to D3. That is, the two slits included in the first opening 24a have a width near the intersection of the width of the vicinity of the end portion.

The electric field in the slit is largest at the central portion and zero at the end. In the case of the first opening 24a of the cross groove shape, since the two electric fields are combined at the intersection portion, the electric field in the intersection portion becomes strong.

The inventors of the present invention have found that in the configuration shown in Fig. 11B, by providing the waveguide structure portion 28 with the first opening 24a having the above-described shape, excessive electric field concentration in the intersecting portion can be suppressed.

In particular, the inventors of the present invention have found that among the angles C1 to C4 of the intersections of the first openings 24a, the most downstream side of the microwave transfer direction Z, that is, the position farthest from the coupling portion 7 When the corner C4 has a curved shape having the smallest curvature, the effect of suppressing electric field concentration can be remarkable. According to this configuration, the waveguide structure portion having higher reliability can be constructed.

The reason for this phenomenon is considered to be an electric field generated around the second opening 14b and an electric field generated around the angle C4 of the first opening 24a, particularly the first opening 24a closest to the second opening 14b. Bring some impact.

Further, the shape of the corner in the intersection of the first opening 24a is not limited to the curved shape shown in FIG. 11B. It suffices that the first opening 24a can have a slit having a width near the intersection of the width of the vicinity of the end portion. The shape of the cross groove can be formed. For example, an angle of a substantially curved shape formed by a plurality of straight lines may be formed at the intersection of the cross groove shape. The angle C1 to the angle C3 may have the same shape as the angle C4.

The angle of the intersection portion in the second opening 14b, in particular, the most upstream side in the microwave transfer direction Z, that is, the angle located closest to the coupling portion 7, even if it has the first opening shown in FIG. 11B The same effect can be obtained by the same shape of the angle C4 of 24a.

The flat region between the two first openings 14a is a passage that extends from the coupling portion 7 toward the front opening 13 along the tube axis V to become a microwave radiated from the front opening 13.

When the distance L1 (= 2 × Y) (refer to FIG. 11A) between the openings in the flat region is excessively large, the heating in the central portion of the mounting surface 6a is suppressed, and the performance of uniform heating is lowered. When the distance L1 is too small, the performance of local heating (directivity of heating) is lowered.

Then, in order to investigate the distance L1 which can improve the performance of uniform heating and the performance of local heating, the inventors conducted the following first experiment to the third experiment, and verified it by CAE.

In the first experiment, in order to investigate the distance L1 for improving the performance of uniform heating, the frozen Osaka fired on the central portion of the mounting surface 6a was heated with the distance L1 as a parameter. In this experiment, the performance of uniform heating was evaluated by focusing on the center temperature of Osaka burning.

In the second experiment, the two-disc frozen sizzling which has been placed on the mounting table 6 was heated with the distance L1 as a parameter and the interval was set. In the second experiment, the two-disc heated objects are separated by an interval substantially 1/4 of the width of the mounting table 6, The center line J (see FIG. 2B) which is symmetrical with respect to the left-right direction of the power supply chamber 2b is arranged on the mounting table 6. Nine frozen sizzlings arranged in three rows and three columns were loaded on each of the disks (about 150 mm in diameter).

Fig. 12 is a schematic view showing a state in which two trays (plates K1, K2) placed on the placing surface 6a are placed at an interval as seen from above in the second experiment. In FIG. 12, in order to show which direction the rotating antenna 5 is facing below the mounting surface 6a, the rotating antenna 5 is shown for convenience.

As shown in Fig. 12, the plates K1, K2 are each arranged such that the center is located from the both edges of the mounting surface 6a to a quarter of the width of the mounting surface 6a. That is, in the three-point chain line in which the mounting surface 6a is divided into four equal parts in the width direction, the plate K1 is disposed on the leftmost dot chain line, and the plate K2 is disposed on the rightmost dot chain line. Hereinafter, such a configuration is referred to as a space configuration.

Since the width of the general mounting surface 6a is about 400 mm, when arranged as shown in Fig. 12, a space is formed between the two plates. In the second experiment, by controlling the rotating antenna 5 so that the front opening 13 is stopped toward the left side, the plate K1 is heated intensively, thereby examining the relationship between the heating directivity and the distance L1. .

The directivity of heating is evaluated based on the ratio of the rising temperature of the object to be heated on the plate K1 to the rising temperature of the object to be heated on the plate K2 (hereinafter referred to as a left/right ratio). The larger the left-to-left ratio, the higher the directivity of heating, which means that the local heating performance is good. The rising temperature refers to the temperature difference before and after heating of the object to be heated.

In the third experiment, the distance L1 is taken as a parameter, and the heating is not set. The two trays arranged on the mounting surface 6a are chilled and sold. In the third experiment, the two-disc heated object was brought into contact with the center of the mounting surface 6a, and arranged symmetrically with respect to the center line J. Hereinafter, such a configuration is referred to as an abutment configuration.

Fig. 13 is a schematic view showing a state in which two trays (plates K1, K2) placed on the placing surface 6a are brought into contact with each other as seen from above in the third experiment. In FIG. 13, in order to show which direction the rotating antenna 5 is facing below the mounting surface 6a, the rotating antenna 5 is shown for convenience.

In the third experiment, the relationship between the directivity of heating and the distance L1 was investigated by controlling the rotating antenna 5 so that the front opening 13 was stopped toward the left side to collectively heat the plate K1. In the third experiment, the directivity of heating was also evaluated based on the left-right ratio.

In other words, the left-right ratio in the second experiment means the left-right ratio at the time of the interval arrangement, and the left-right ratio in the third experiment means the left-right ratio at the time of the contact arrangement.

The microwave suction opening 14 shown in FIG. 11B in the first condition (when the distance L1 is 12 mm), the second condition (when the distance L1 is 15 mm), and the third condition (when the distance L1 is 18 mm) The position and size of each part will be described using FIG. 14 and Table 1.

Fig. 14 shows the positions of the respective portions of the microwave suction opening 14 shown in Fig. 11B, and Table 1 shows the dimensions of the respective portions from the first condition to the third condition.

As shown in FIG. 14 and Table 1, in the first condition to the third condition, the second length B of the microwave suction opening 14 is set to be sequentially shortened, and the distance L1 is set to be sequentially increased. Specifically, in the first condition, the second length is 25.5 mm, and the distance L1 is 12 mm; in the second condition, the second length is 23.5 mm, and the distance L1 is 15 mm; In the third condition, the second length was set to 21.5 mm, and the distance L1 was set to 18 mm.

Fig. 15 is a view showing the results of the first experiment to the third experiment using the distance L1 as a parameter. The right vertical axis of Fig. 15 shows the temperature of the center portion of the Osaka-fired portion measured in the first experiment. The left vertical axis of Fig. 15 shows the left-right ratio calculated in the second experiment and the third experiment.

Here, the results of the first experiment will be described.

As shown in Fig. 15, in the first to third conditions, the temperature of the central portion of the object to be heated is about 80 to 92 °C. After the experiment was conducted under the same conditions using the microwave oven 200 described in Patent Document 2, the temperature of the center portion of the object to be heated was 74 °C.

These results show that, with the configuration shown in FIG. 11B, in the range of the distance L1 of 12 to 18 mm, it is sufficiently heated compared with the prior art. The center of Sakae. According to this configuration, the performance of uniform heating can be improved.

Next, the results of the second experiment and the third experiment will be described.

As shown in FIG. 15, in the second experiment, the left-right ratio in the first condition to the third condition was 2.9 to 4. In the third experiment, the left-right ratio in the first condition to the third condition was 4.4 to 5.3. After the experiment was carried out under the same conditions using the microwave oven 200 described in Patent Document 2, the right and left ratios in the second experiment and the third experiment were 2.3 and 3.2, respectively.

These results show that, in the configuration shown in FIG. 11B, in the range of the distance L1 of 12 to 18 mm, the left-right ratio is increased as compared with the prior art. According to this configuration, the performance of local heating can be improved.

Ideally, it is preferred that, for example, the three objects to be heated are locally heated regardless of the arrangement position. From the results of the experiment, the inventors have found that when the left-right ratio at the time of the interval arrangement is 3.5 or more, this ideal local heating (that is, high-efficiency local heating of the three objects to be heated) is possible. Therefore, the distance L1 is preferably set to a range of 15 to 18 mm in which the right and left ratio when the interval is arranged is 3.5 or more.

As described above, by setting the distance L1 in the range of 15 to 18 mm, it is possible to optimize the uniformity of the heating distribution for uniform heating and the directivity for heating for local heating.

Of course, the technical idea of the present invention is not limited to the above specific dimensions. For example, the distance L1 should be changed in accordance with the size of the microwave heating device. The distance L1 is preferably set to be about 1/8 to 1/4 of the distance L2 between the side wall surface 10a and the side wall surface 10c (that is, the width of the waveguide structure portion 8 (see FIG. 11A)). In the above embodiment, the distance L1 is almost equal to the shaft diameter of the coupling shaft 7a.

In the above experiment, the second length B is shortened to lengthen the distance L1, but not limited thereto. Alternatively, when the first length A to the fourth length D are not changed, the distance L1 can be set to a desired size by changing the intersection angle of the two slits forming the first opening 14a.

16A and 16B are plan views showing microwave suction openings 34 of other shapes. As shown in FIGS. 16A and 16B, the waveguide structure portion 38 has a microwave suction opening 34 provided on the top surface 39. The microwave suction opening 34 includes a first opening 34a and a second opening 14b. The first opening 34a differs from the first opening 14a shown in FIG. 11A and the first opening 24a shown in FIG. 11B in the intersection angle of the two slits.

Specifically, the slit 20e of the first opening 34a has the same length as the slit 20a of the first opening 14a and the slit 20c of the first opening 24a. The long axis of the slit 20e is oriented in the same direction as the long axis of the slit 20a and the long axis of the slit 20c (see FIGS. 11A and 11B).

However, as shown in FIGS. 16A and 16B, when the long axis of the slit 20f is made close to the tube axis V, the distance L1 can be set larger even if the same second length B is provided.

As described above, according to the present disclosure, it is possible to uniformly heat and locally heat the object to be heated.

In addition to the microwave oven, the present disclosure can be utilized in various industrial microwave heating apparatuses such as a drying apparatus, a ceramic heating apparatus, a kitchen processing machine, and a semiconductor manufacturing apparatus.

5‧‧‧Rotating antenna

7‧‧‧Coupling Department

7a‧‧‧Coupling axis

7b‧‧‧Flange

8‧‧‧guide tube structure department

9‧‧‧ top surface

9a‧‧‧ recess

10a, 10b, 10c‧‧‧ side wall

12‧‧‧Low Impedance Department

12a‧‧‧slit

13‧‧‧ front opening

14‧‧‧Microwave suction opening

14a‧‧‧1st opening

14b‧‧‧2nd opening

19‧‧‧ Keeping Department

G‧‧‧ Rotation Center

W‧‧‧Width direction

Z‧‧‧Microwave transmission direction

Claims (4)

A microwave heating device comprising: a heating chamber for accommodating an object to be heated; a microwave generating unit for generating microwaves; and a waveguide structure antenna having a top surface, a side wall surface, and a front opening of the predetermined waveguide structure portion, and a waveguide structure antenna that radiates microwaves from the front opening to the heating chamber, the waveguide structure portion having a coupling portion that is coupled to the top surface and that couples the microwave to the waveguide structure portion The inner space, the waveguide structure portion has at least one microwave suction opening formed on the top surface, and radiates a circular polarization wave from the microwave suction opening into the heating chamber, wherein the at least one microwave suction opening comprises at least one pair of symmetry The microwave suction opening of the tube axis of the waveguide structure portion, and the waveguide structure portion has a flat region between the pair of microwave suction openings. The microwave heating device of claim 1, wherein each of the pair of microwave suction openings has a cross groove shape in which two slits intersect, and between the pair of microwave suction openings, a slit closer to the coupling portion The distance is longer than the distance between the slits far from the aforementioned coupling portion. A microwave heating device according to claim 2, comprising: a driving unit that rotates the antenna of the waveguide structure; The coupling portion includes a coupling shaft that is coupled to the driving portion and includes a rotation center of the waveguide structure antenna, and a flange that is provided around the coupling shaft to form a joint portion, and the pair is closer to the coupling portion The microwave suction opening is disposed close to the edge of the joint portion. The microwave heating apparatus of claim 1, wherein a distance between the pair of microwave suction openings is 1/8 to 1/4 of a width of the waveguide structure portion.